1. Field of the Invention
The present invention relates to protective flux coatings for use in the plumbing, refrigeration and HVAC industries, and to a process for applying and utilizing such coatings by applying thin, protective flux films to parts such as tubing, valves, fittings, heat exchange elements, etc. More particularly, the present invention relates to a process for applying thin protective flux films to cleaned metal surfaces of the discussed parts, whereby soldering joining operations can be rapidly effected after long periods of storage or delay, and also relates to simple flux coating solutions used in generating the protective flux films.
2. Description of Relevant Art
Conventional soldering processes for fluid-tightly joining components include three basic steps: (1) preparation of components to be soldered by cleaning the surfaces to be joined to ensure the surfaces are free of contaminants and applying a flux to the cleaned surfaces; (2) joining the cleaned and fluxed surfaces of the components by fitting the components together, applying heat to fitted components and applying solder to the heated surfaces; and (3) cleaning the joined components of residual flux and solder, commonly known as "wiping the joint".
There are many known soldering fluxes used in the plumbing industry, the refrigeration industry and the heating, ventilating and air-conditioning (HVAC) industry for joining components such as tubing, valves, fittings, heat exchange elements, etc. which are comprised of copper and/or copper alloys. The known soldering fluxes are in paste form, liquid form, powder form, gaseous form and integral solder/flux form. All of the known fluxes are designed to be used within a relatively short period of time (minutes) between preparation of the components, by cleaning the appropriate surfaces and applying the fluxes thereto, and joining operations involving the fluxed components. Paste fluxes are by their nature untidy, usually having petroleum jelly as a carrier or base. The untidy nature of paste renders any intermediate operations involving the fluxed parts difficult, and paste consistency leaves no durable protective coating. Liquid fluxes which are watery for ease of use and penetration, leave no durable protective film and are designed for immediate use. Powder fluxes are either mixed with a fluid to form a paste or are used in a powder form. In either form, the powder fluxes are also untidy, designed for immediate use, and leave no durable protective coating. Gaseous fluxes create an atmosphere about the parts to be soldered. As will be understood, gaseous fluxes have limited applicability (they cannot be used under field conditions or the like) because of their very nature, and leave no durable protective coating. Integral solder/fluxes by their very nature prohibit the interjection of time between preparation and joining of parts.
The known soldering fluxes are disadvantages for use in the plumbing, refrigeration and HVAC industries for several reasons. One significant reasons is the requirement of soldering the flux coated components within a short time after the flux coatings have been applied thereto. In other words, there cannot be any substantial pause between the first two steps of the conventional soldering process discussed above. This requirement substantially increases the time and inconvenience conventionally associated with soldering of plumbing, refrigeration and HVAC components at a job site inasmuch as the components cannot be pre-fluxed at a more convenient location (such as a workshop) and then transported to the job site for completing the soldering process.
Furthermore, the known flux coatings are generally rather messy and/or difficult to handle; cannot be easily applied to parts in a highly uniform manner.
Also, most soldering processes using known fluxes result in a quantity of excess flux and flux carrier remaining on the components after they have been soldered together, whereby the excess flux and flux carrier must be removed from the components in the final (cleaning) step of the conventional soldering process discussed above.
Another disadvantage associated with many conventional fluxes, particularly petroleum jelly based fluxes, occurs when components are being soldered together above the person performing the soldering operation. In such situations the heated flux can, in part, drip or flow down on the person inflicting a skin burn.
The present invention effectively overcomes the problems and disadvantages attendant to conventional soldering fluxes used in the plumbing, refrigeration and HVAC industries. Relatedly, the present invention significantly facilitates the soldering processes used in the discussed industries, and permits the inclusion of other optional operations such as storage, transportation and forming of components between the conventional fluxing and joining steps.
Many of the advantages of the present invention when applied to soldering operations are also available to low temperature brazing operations.